NCERT Solutions for Class 7 Science Chapter 15 – Light

Question 1

Fill in the blanks:
(a) An /Pathanto/image that cannot be obtained on a screen is called ___________ .
(b) /Pathanto/image formed by a convex is __________ always virtual and smaller in size.
(c) An /Pathanto/image formed by a __________ mirror is always of the same size as that of the object.
(d) An /Pathanto/image which can be obtained on a screen is called a __________ /Pathanto/image.
(e) An /Pathanto/image formed by a concave __________ cannot be obtained on a screen.

Answer

(a) An /Pathanto/image that cannot be obtained on a screen is called virtual /Pathanto/image .
(b) /Pathanto/image formed by a convex is mirror always virtual and smaller in size.
(c) An /Pathanto/image formed by a plane mirror is always of the same size as that of the object.
(d) An /Pathanto/image which can be obtained on a screen is called a real /Pathanto/image.
(e) An /Pathanto/image formed by a concave lens cannot be obtained on a screen.

Question 2

Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) We can obtain an enlarged and erect /Pathanto/image by a convex mirror. (T/F)
(b) A concave lens always form a virtual /Pathanto/image. (T/F)
(c) We can obtain a real, enlarged and inverted /Pathanto/image by a concave mirror. (T/F)
(d) A real /Pathanto/image cannot be obtained on a screen. (T/F)
(e) A concave mirror always form a real /Pathanto/image. (T/F)

Answer

a) False

b) True

c) True

d) False

e) False

Question 3

Match the items given in Column I with one or more items of Column II

Answer

Question 4

State the characteristics of the /Pathanto/image formed by a plane mirror.

Answer

(i) Plane mirror forms an erect and virtual /Pathanto/image.
(ii) height of the /Pathanto/image and object are equal.
(iii)Distance of /Pathanto/image and object from mirror are equal.
(iv) /Pathanto/image formed laterally inverted

Question 5

Find out the letters of English alphabet or any other language known to you in which the /Pathanto/image formed in a plane mirror appears exactly like the letter itself. Discuss your findings.

Answer

A, H, I, M, O, T, U ,V, W These letter appear same when we seen through a plane mirror

Question 6

What is a virtual /Pathanto/image? Give one situation where a virtual /Pathanto/image is formed.

Answer

The /Pathanto/image which formed behind the mirror is called virtual /Pathanto/image.These /Pathanto/image can not obtain on mirror.

Question 7

State two differences between a convex and a concave lens.

Answer

Question 8

Give one use each of a concave and a convex mirror.

Answer

Concave mirror is used in solar furnaces to conserve sunlight.
Convex mirror is used as side view mirror in vehicles

Question 9

Which type of mirror can form a real /Pathanto/image?

Answer

Concave mirror

Question 10

Which type of lens forms always a virtual /Pathanto/image?

Answer

Concave lens

Choose the correct option in Questions 11-13:

Question 11

A virtual /Pathanto/image larger than the object can be produced by a
(i) concave lens (ii) concave mirror (iii) convex mirror (iv) plane mirror

Answer

(ii) concave mirror

Question 12

David is observing his /Pathanto/image in a plane mirror. Die distance between the mirror and his /Pathanto/image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his /Pathanto/image will be
(i) 3 m (ii) 5 m (iii) 6 m (iv) 8 m

Answer

(iii) 6 m

Question 13

The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rear mew mirror the /Pathanto/image of a truck parked behind his car. The speed at which the /Pathanto/image of the truck appears to approach the driver will be
(i) 1 m/s (ii) 2 m/s (iii) 4 m/s (iv) 8 m/s

Answer

(ii) 4 m/s